Ask any comic-book reader who scratched his head at Jane Foster's work as an astrophysicist or Bucky's prewar friendship with Steve Rogers: The Marvel Cinematic Universe is distinctly different from the comic books and has its own unique history. So how do you keep that history straight? You don't. Two fans have already done it for you.
Rich Drees, the editor/publisher of Film Buff Online, wrote an initial timeline, which was later embellished by Andrew Norfolk, documenting all the major events that happened in the MCU. It's astonishing work.
It starts with the attack of Dark Elves, back in 2987 BC. Other events include young Tony Stark building his first circuit board and Hydra attacking Guernica (!?)—and pinning the blame on the Luftwaffe. Some of these entries have lengthy descriptions, which will impress even the most detail-oriented among us.
The site is laid out in an easy-to-browse manner and includes screenshots of the references, and in some cases timestamps from the nine movies (and counting) the item is referencing. But it's not just the movies that this timeline covers. Important events from Agents of SHIELD are also highlighted, as well as comic books that tie in to the MCU.
It's a fun browse for any fan who has ever wondered when Howard Stark located the tesseract. Check it out here.